Hammond, 48, and fellow MIT researchers make superthin batteries that can store a lot of energy and discharge—and charge—rapidly.

"We make a battery with carbon nanotubes as the electrode. These materials give us behavior that is like a traditional battery in that it relies on chemical reactions, but they also give us behavior like a regular capacitor—which stores energy without using any chemical reactions. This is important because, while batteries store a lot of energy, you generally can't pull that energy down rapidly, which means they're low power. That limits them when you need a surge of power—for starting a car engine, for instance. Electrochemical capacitors, on the other hand, discharge the energy they store rapidly. Those carbon nanotubes help us have both of the good things: We can get battery-style energy-storage capability with extremely high power, so energy can be released rapidly."